JPH08233939A - Light wave rangefinder - Google Patents

Abstract

PURPOSE: To enhance the efficiency and the accuracy of the measurement of a range by regulating the light reception amount of light receiving means by the mean value of a light receiving level, deciding the time for holding a light receiving peak value by starting from the light receiving timing, selecting only the pulse of the level in a predetermined range by a calculator, and calculating the range. CONSTITUTION: A measuring laser beam quantity is detected by a light receiving unit 154 having a light receiving element 120 and a photodetector 150, and output to a CPU 154, which calculates the control signal of a driving circuit 158. The circuit 158 controls to drive a drive motor 164 of a light quantity attenuating filter based on it. A peak level detector 170 charges the input signal in a capacitor 44 via an electronic switch 10 which is turned ON at the light emitting timing, and stored as a light receiving peak value. The switch 10 is turned OFF at the receiving timing, and thereafter a noise signal is prevented from being input to the capacitor 44. Thus, a correct light quantity level can be always detected irrespective of the measured range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source section which emits light in a pulsed manner, an optical means for sending light from the light source section to an object to be measured, and a reflection term from the object to be measured. Then, the light wave measuring device has a light receiving unit for converting the received signal into an electric signal and a calculating unit for calculating the distance to the object to be measured from the time difference between the light emitting timing of the light source unit and the light receiving timing of the light receiving unit. A distance device.

[0002]

2. Description of the Related Art A conventional light-wave distance measuring device, that is, a light source section which emits light in a pulsed manner, an optical means for sending light from the light source section to an object to be measured, and reflected light from the object to be measured. Having a light receiving means for receiving the light and converting it into a received pulse of an electric signal, and a calculation portion for calculating the distance to the object to be measured from the time difference between the light emitting timing of the light source portion and the light receiving timing of the light receiving means. In the optical distance measuring device, the reflected light from the object to be measured and the optical path light inside the main body are measured to cancel the error of the device and improve the measurement accuracy. Further, there is provided a light amount adjusting device for keeping the reflected light and the optical path light constant so that the characteristics of the light receiving element due to the difference in the received light amount do not affect the measurement accuracy. On the other hand, the light source section periodically emits pulsed light, and its cycle is, for example, 100
Since the microsecond and the pulse width are 20 nanoseconds, it is impossible to detect the light quantity level of the pulsed light for each. Therefore, the average value of the light receiving level values of the pulsed light within a fixed time for adjusting the light receiving amount is used. The integrated value obtained from the time from the light reception to the reset and the light reception peak value is calculated by averaging the integrated values within a fixed time. The reset of the light reception peak value holding is determined by the time calculated from the light emission timing.

[0003]

In the above-described conventional lightwave distance measuring device, since the generation of the reset signal for holding the received light peak value is determined by the time counted from the light emission timing, the distance measuring distance is different. Then, the time for holding the received light peak value, that is, the time from the light reception to the reset differs depending on the surveying distance. When the measuring distance is long, it is short, and when the measuring distance is short, it is long, and the integral value varies accordingly. Originally, using the product value of the peak values according to the amount of received light,
The light amount is adjusted by obtaining the average value of the integrated values within a predetermined time, but the average value is affected by the measurement distance.For example, when the measurement distance is long, the average value is set low and the input light amount is set to the appropriate light amount. You will not be able to adjust to the level. As a result, there are problems that the measurement error becomes large, the distance measurement efficiency is reduced, and the measurement is stopped in some cases.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the conventional lightwave distance measuring apparatus, and it is possible to always detect the correct light quantity level regardless of the size of the measuring distance and to make it suitable. An object of the present invention is to provide an optical wave distance measuring device capable of adjusting received light amount and performing efficient and highly accurate measurement.

[0005]

According to the present invention, there is provided a light source section which emits light in a pulsed manner, an optical means for sending light from the light source section to an object to be measured, and a reflected light from the object to be measured. It has a light receiving means for converting it into a received pulse of an electric signal, and a computing part for computing the distance to the object to be measured from the time difference between the light emitting timing of the light source and the light receiving timing of the light receiving means. The means has a received light amount adjusting means for adjusting the amount of received light according to the average value of the received light level, and the time during which the light receiving means further holds the received light peak value is determined by calculating from the light receiving timing, and the calculating part receives light within a certain range. It is an optical distance measuring device characterized in that only a received pulse of a level is selected and a distance calculation is performed. The present invention also provides a light source unit that emits light in a pulsed manner, an optical unit for sending light from the light source unit to a measurement target, and a reflected light from the measurement target to receive an electrical signal. The light receiving means for converting into a pulse, and the operation part for calculating the distance to the object to be measured from the time difference between the light emission timing of the light source part and the light receiving timing of the light receiving part, the light receiving means, An optical wave distance measuring device having a one-shot multivibrator for generating a reset signal of a capacitor for holding a peak value of a received light signal after a fixed time counted by timing.

[0006]

The light receiving means generates a capacitor reset signal for holding the light receiving signal peak value after a fixed time calculated based on the light receiving timing by the one-shot multivibrator, so that the average value of the light receiving peak values can be accurately calculated. The calculation can be performed, and an appropriate received light amount adjustment can be performed by the accurate average value of the peak values.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical wave distance measuring apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The distance measuring optical system of the optical distance measuring device is shown in FIG.
As shown in FIG. 3, the pulse laser beam or the modulated laser beam emitted from the laser light source 100 is passed through the rotary light-shielding desk 102, the right-angle prism 104, and the objective lens 106, or the distance measurement target 108 or the reflecting mirror 110 placed there.
Project towards. When a pulsed laser beam is used, the reflecting object may be the object to be measured 108 or a reflecting mirror. The modulated laser beam may be the object to be path-measured itself. Use is desirable. The distance measuring laser light flux reflected by the distance measuring object 108 or the reflecting mirror 110 reaches the light receiving element 120 via the right-angle prism 104, the objective lens 106, and the light amount attenuation filter 112. The light amount of the distance measuring laser light flux incident on the light receiving element 120 is adjusted by the light amount attenuation filter 112. The reference light optical system is a half mirror 1 arranged between a laser light source 100 and a rotating light-shielding desk 102.
The reference laser beam split by 30 is passed through the mirror 1
32, a rotary shading desk 102, a pair of relay lenses 13
4, 136, a mirror 138, and a half mirror 140 arranged between the light amount attenuation filter 112 and the light receiving element 120 to make the light incident on the light receiving element 120. The laser light flux emitted from the laser light source 100 is alternately emitted as a distance measurement laser light flux and a reference laser light flux by the rotation of the rotary light-shielding desk 102.

The control of the light amount attenuation filter 112 is shown in FIG.
As shown in, the light receiving unit 154 including the light receiving element 120 and the light detecting unit 150 detects the light amount of the distance measuring laser light flux, that is, the distance measuring laser light amount, and outputs it to the CPU 156. The CPU 156 calculates a control signal of the drive circuit unit 158 based on the distance measurement laser light amount, and outputs a light amount control signal of the reference laser light flux to the drive circuit unit 158. The drive circuit unit 158 drives and controls the drive motor 164 of the light amount attenuation filter 112 based on the input light amount control signal. As shown in FIG. 1, the peak level detection circuit of the lightwave distance measuring device is configured such that the first input signal is turned on at the light emission timing.
The capacitor 44 is charged through the electronic switch 10 and held as a light reception peak value. The first electronic switch 10 is configured to turn on at the light emission timing and turn off at the light receiving timing. When the first electronic switch 10 is turned off at the light receiving timing, a noise signal is input to the capacitor 44 after the light receiving timing, and an erroneous peak value signal including a noise component 200 shown by a diagonal line to the lower right of FIG. 2 is charged. This is to prevent this.

The input signal is also input to the one-shot multivibrator 14 and the one-shot multivibrator 1 is input.
4 is a control of the input light receiving signal by the SW10 switch and S
The reset signal of the capacitor is controlled by the W16 switch. The reset signal is a discharge start signal for keeping the capacitor 44 in a discharging state for a certain time in view of the time required for discharging the capacitor 44. The reset release signal, which is a discharge end signal, is controlled by the CPU in the same manner as the light emission for generating before the predetermined light emission. The one-shot multivibrator 14 outputs a reset signal to the second electronic switch 16 after a lapse of a fixed time from the light receiving timing, and further outputs a reset release signal to the second electronic switch 16 after a lapse of the fixed time from the light emitting timing. That is, as shown in FIG. 2, the reset release signal is generated when the light emission timing holding circuit is shifted in the early direction from the light emission timing by the time required for the setup time of the light receiving peak holding circuit.
By generating the reset release signal just before the light emission timing in this way, a noise signal input to the capacitor 44 from the generation of the reset release signal to the light reception timing, that is, the bias component 202 indicated by the slanted line in the lower left of FIG. Make the input as small as possible.

A first resistor 26 connected to the power supply 24 and a second resistor 27 grounded maintain one side of the first capacitor 12 at a constant potential. Third connected to power supply 24
The resistor 30 drives the transistor 32. The coil 40 connected to the transistor 32 removes the DC component of the input signal, that is, the bias component. The diode 42 and the second capacitor 44 detect the input signal. The buffer amplifier 46 prevents the peak value signal output from the diode 42 and the second capacitor 44 from drooping and holds the peak value. The level of the peak value signal output via the buffer amplifier 46 is determined by the level determination circuit 50. As a result of this determination, if the amount of received light needs to be adjusted, the light amount attenuation filter 1 is passed through the drive circuit unit 158.
The 12 drive motors 164 are driven to adjust the amount of received light.

[0011]

According to the optical distance measuring apparatus of the present invention, the correct light quantity level is always detected regardless of the size of the measuring distance, and the appropriate received light quantity is adjusted to perform efficient and highly accurate measurement. Has the effect that can be done.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a received light amount adjusting system of a lightwave distance measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart diagram for explaining the operation of the received light amount adjustment system of the lightwave distance measuring apparatus according to the embodiment of the present invention.

FIG. 3 is a structural explanatory view of a lightwave distance measuring apparatus according to an embodiment of the present invention.

FIG. 4 is a block diagram of a light receiving amount adjustment system of the lightwave distance measuring apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 10 First Electronic Switch 12 First Capacitor 14 1-Shot Multivibrator 16 Second Electronic Switch 24 Power Supply 26 First Resistor 27 Second Resistor 30 Third Resistor 32 Transistor 40 Coil 42 Diode 44 Second Capacitor 46 Buffer Amplifier 50 Level Judgment Circuit 102 Rotation Shading Desk 104 Right Angle Prism 104 106 Objective Lens 108 Distance Measurement Object 110 Reflector 112 Light Attenuation Filter 120 Light-Receiving Element 130 Half Mirror 150 Photodetector 152 A / D Converter 156 Microcomputer 164 Drive Motor 200 Noise Component 202 Bias Component

Front page continued (72) Inventor Takeshige Saito 75-1 Hasunumacho, Itabashi-ku, Tokyo Topcon Co., Ltd.

Claims (2)

[Claims] 1. A light source section that emits light in a pulsed manner, an optical means for sending light from the light source section to an object to be measured, and a reflected light from the object to be measured to receive an electrical signal. It has a light receiving means for converting it into a pulse, and a computing part for computing the distance to the object to be measured from the time difference between the light emitting timing of the light source and the light receiving timing of the light receiving means, and the light receiving means has a light receiving level. The light receiving amount adjusting means for adjusting the light receiving amount according to the average value of the light receiving amount is calculated, and the time when the light receiving means further holds the light receiving peak value is calculated from the light receiving timing. An optical wave distance measuring device characterized in that a distance calculation is performed by selecting it. 2. A light source section which emits light in a pulsed manner, an optical means for sending the light from the light source section to an object to be measured, a reflected light from the object to be measured, and an electric signal reception. The light receiving means for converting into a pulse, and the operation part for calculating the distance to the object to be measured from the time difference between the light emission timing of the light source part and the light receiving timing of the light receiving part are provided. An optical wave distance measuring device comprising a one-shot multivibrator that generates a reset signal for a capacitor for holding a peak value of a received light signal after a fixed time counted by timing.